394 



the Heat developed hi Combustion 



to separate them entirely ; and as both are colourless and 

 limpid, either when mixed or separate, we can scarcely 

 judge of the degree of purity of the ether, except by its 

 specific gravity, and even in this way but very imperfectly. 



The most highly rectified sulphuric ether which I could 

 procure, and which I employed in my experiments, was 

 prepared in M. Vauquelin's laboratory. Its specific 

 gravity is 728.34 at the temperature of 16 Reaumur. 

 As that which was employed by M. de Saussure in his 

 analysis was only of the specific gravity of 717 at the 

 same temperature, by regarding the ether which I em- 

 ployed as being a mixture of the same degree of purity 

 with that of M. de Saussure, and the pure alcohol of 

 Lowitz having a specific gravity of 792, we shall find, 

 upon making a calculation, that the ether which I em- 

 ployed was a mixture of 85 parts of ether of the spe- 

 cific gravity of 717, and 15 parts of pure alcohol of Lo- 

 witz of the specific gravity of 792. 



On burning this mixture under my calorimeter, after 

 having brought my apparatus to the highest degree of 

 perfection, I obtained the following results : 



